Boneco AIR-O-SWISS Ultrasonic Humidifiers are the quietest humidifiers on the market, using a high quality transducer surface and adjustable high-frequency vibrations to turn water into a micro-fine mist. Boneco AIR-O-SWISS Ultrasonic Humidifiers are ideal for small to medium sized rooms, and are the top of the line choice when looking for the quietest and best quality room humidifiers. Available in Cool Mist or Dual Warm/Cool Mist models, and with mechanical or digital controls.